1. Field
Disclosed herein is a blood pressure measuring device for measuring a blood pressure of a patient either once or continuously.
2. Description of the Related Art
Various types of blood pressure measuring devices have been developed in the interests of monitoring the blood pressure of individuals and thereby improving the public health. Blood pressure measuring methods include a Korotkoff sounds method, an oscillometric method, a tonometric method, and the like. The Korotkoff sounds method, which is a typical blood pressure measuring method, measures the systolic pressure at which the pulse sound is first heard and the diastolic pressure at which the pulse sound is barely audible in a depressurization process after blood flow is blocked by sufficiently pressurizing a body part through which arterial blood flows.
The oscillometric method and the tonometric method are used in digital blood pressure measuring devices. The oscillometric method measures the systolic pressure and the diastolic pressure by detecting a pulse wave generated in a depressurization process that depressurizes a body part at a constant speed. The detection of the pulse wave is conducted after sufficiently pressurizing the body part through which arterial blood flows so as to block arterial blood flow. This is similar to the Korotkoff sounds method. The oscillometric method may also be conducted in a pressurization process that pressurizes the body part at a constant speed. A pressure at which the amplitude of a pulse waveform is at a specific level may be measured as a function of the systolic pressure or the diastolic pressure, as compared to a pressure at which the amplitude of the pulse waveform is at a maximum. Alternatively, a pressure at which the amplitude of the pulse waveform varies greatly may be measured as a function of the systolic pressure or the diastolic pressure. During the depressurization process of the body part at a constant speed after the pressurization process, the systolic pressure is measured before the moment at which the amplitude of the pulse waveform is at the maximum, and the diastolic pressure is measured after the moment at which the amplitude of the pulse waveform is at the maximum. On the contrary, in the pressurization process of the body part at a constant speed, the systolic pressure is measured after the moment at which the amplitude of the pulse waveform is at the maximum, and the diastolic pressure is measured before the moment at which the amplitude of the pulse waveform is at the maximum.
The tonometric method compresses a body part so that arterial blood flow is not completely blocked and continuously measures blood pressure by using the size and form of a sphygmus wave generated by pressurizing the body part.
Recently, a portable blood pressure measuring device, which can measure blood pressure by using an oscillometric method or a tonometric method without any inconvenience to a user has been developed. The portable blood pressure measuring device can be installed in a body part such as a wrist. However, the portable blood pressure measuring device needs improvement in terms of size and precision control of blood vessel pressurization pressure.